1. Field of the Invention
The present invention relates to a projection type picture display apparatus in which pictures output from a projection unit are projecting to a back face of a screen to thereby display the pictures.
2. Description of the Related Art
The prior art is shown FIGS. 7-11. In FIGS. 7-11, xe2x80x9cXxe2x80x9d, xe2x80x9cYxe2x80x9d and xe2x80x9cZxe2x80x9d show the Z-axis, Y-axis and Z-axis of the three dimension space. FIG. 7 is a side view showing the inside of a conventional multi-projector. Here, the multi-projector described above means a display apparatus which is designed to display a large display frame (picture) by arranging and stacking plural projection type picture display apparatuses (rear projection type video projectors) vertically and horizontally. In FIG. 7, it is illustrated that two conventional projection type picture display apparatuses 160 are stacked in the vertical direction.
As shown in FIG. 7, the projection type picture display apparatus comprises a cabinet (the housing of the projection type picture display apparatus) 101, a projection unit 102 which is disposed at the rear side in the cabinet 101 and projects an output picture to the front side, a screen 103 provided at the front face of the cabinet 101, and a position adjusting mechanism 150 for correcting a position of a outline of a picture to be projected from the projection unit 102 to the screen 103. The projection unit 102 projects an output picture to a back face of the screen. A large display frame can be displayed by combining and using a plurality of projection type picture display apparatuses 160 each having the above structure. In this case, the projection unit 102 is secured to the upper portion of the position adjusting mechanism 160 so that the position thereof is adjustable.
FIGS. 8 to 10 are diagrams which conceptually show pictures displayed on the screen 103 while each picture is displaced with respect to the screen 103. As displacements on the screen 103 exist six kinds of displacements which are a vertical displacement (a displacement in the vertical direction), a horizontal displacement (a displacement in the right-and-left direction), an inclining displacement, a projection magnification displacement, a longitudinal trapezoidal distortion and a lateral trapezoidal distortion, or a combination thereof.
In FIG. 8, reference numeral 104a represents a picture which is improper in projection magnification to the screen 103 (magnification-improper picture), reference numeral 104b represents a picture which is improperly inclined with respect to the screen 103 (improperly-inclined picture), and reference numeral 104c represents a picture which is improperly displaced in the vertical and horizontal directions with respect to the screen 103 (vertical/horizontal improper picture).
In FIG. 9, reference numeral 104d represents a picture in which a longitudinal trapezoidal distortion occurs (longitudinal trapezoidal improper picture), and in FIG. 10 reference numeral 104e represents a picture in which a lateral trapezoidal distortion occurs (lateral trapezoidal improper picture).
In most cases, Braun tube (CRT) has been mainly applied to the projection unit 102 because the displacements on the screen 103 of the Braun tube can be easily corrected by an electrical circuit. However, in place of the Braun tube, a liquid crystal device or a digital mirror device for which the optical path cannot be electrically corrected have been recently mainly applied to the projection unit 102 because of the tendency of digitalization of pictures. In this case, a position adjusting mechanism 150 is indispensable for the projection unit 102 for which the optical path cannot be electrically corrected.
FIG. 11 is a perspective view showing the outlook of a conventional position adjusting mechanism 150.
In FIG. 11, reference numeral 150a represents a Y-axis moving plate which can move the projection unit 102 in the Y-axis direction, reference numeral 150b represents an Y-axis rotating plate which is rotatable around the Y-axis, reference numeral 150c represents a Z-axis rotating plate which is rotatable around the Z-axis, reference numeral 150d represents an X-axis rotating plate which is rotatable around the X-axis, reference numeral 150e represents a Z-axis moving plate which is movable in the Z-axis direction, and reference numeral 150f represents an X-axis moving plate which is movable in the X-axis direction.
Next, the position adjusting operation of the conventional picture outlook adjusting mechanism 150 shown in FIG. 11 will be described with reference to FIGS. 7 to 11.
A picture projected from the projection unit 102 is projected onto the screen 103. At this time, the projection magnification of the picture can be corrected by the adjusting operation of the Z-axis moving plate 150e. Further, the lateral trapezoidal distortion can be corrected by the Y-axis rotating plate 150b, and the inclination of the picture can be corrected by the adjustment of the Z-axis rotating plate 150c. The longitudinal trapezoidal distortion can be also corrected by the adjustment of the X-axis rotating plate 150d. Still further, the vertical and horizontal position can be corrected by the adjustment of the X-axis moving plate 150f and the Y-axis moving plate 150d. 
Japanese Laid-open Patent Application No. Hei-8-32907 discloses another prior art, and specifically it discloses a technique of separating one display unit (projection type picture display apparatus) into a front side cabinet and a back side cabinet.
As described above, in the conventional projection type picture display apparatuses, six adjusting functions must be adjusted for the position adjusting mechanism 6, and also six adjusting functions must be provided every adjusting mechanism performing only one adjustment. Therefore, the number of parts of the apparatus and the weight of the apparatus are increased, and the cost is also increased.
Therefore, the present invention has been implemented in view of the above circumstances and has an object to provide a projection type picture display apparatus which can reduce the number of parts and the weight.
In order to attain the above object, according to the present invention, a projection type picture display apparatus comprising a projection unit for projecting a picture to a back face of a screen and a position adjusting mechanism for supporting the projection unit and for giving six adjusting functions including X, Y, Z directional adjustments for moving the projection unit along X-axis, Y-axis, Z-axis of three dimension space respectively, and X, Y, Z rotational adjustments for rotating the projection unit around X-axis, Y-axis, Z-axis respectively, characterized in that said position adjusting mechanism has an adjusting plate member for performing three adjusting functions of said six adjusting functions.
The adjusting plate member performs the three adjusting functions including Z rotational adjustment for rotating the projection unit around Z-axis, X rotational adjustment for rotating the projection unit around X-axis, and Y directional adjustment for moving the projection unit along Y-axis.
Further the adjusting plate member has a first support shaft extending in the Y-axis direction, a second support shaft which is disposed so as to be in parallel to said first support shaft and spaced from said first support shaft at a predetermined interval in the Z-axis direction, a third support shaft which is disposed so as to be in parallel to said first support shaft and spaced from said first support shaft at a predetermined interval in the X-axis direction, a first adjusting shaft which is selectively engageable with both of said first and second support shafts or only said second support shaft through a gear switching operation, a second adjusting shaft which is selectively engageable with both said first and third support shafts or only said first support shaft through a gear switching operation, and an adjusting plate is supported on said first, second and third support shafts for supporting the projection unit.
Also the adjusting plate member performs said Z rotational adjustment when said first adjusting shaft engages with both said first and second support shaft and said second adjusting shaft engages with said first support shaft but no-engages with said third support shaft, said X rotational adjustment when said first adjusting shaft engages with said second support shaft but no-engages with said first support shaft and said second adjusting shaft engages with said first support shaft but no-engages with said third support shaft, and said Y directional adjustment when said first adjusting shaft engages with both said first and second support shaft and said second adjusting shaft engages with both said second and third support shafts.
In the projection type picture display apparatus, one end of said first adjusting shaft has a knurled portion on the outer peripheral portion thereof, and said knurled portion is engaged with a member having a knurled portion on the inner peripheral portion thereof to stop the rotation of said first adjusting shaft.
Further the adjusting plate member has a first support shaft extending in the Y-axis direction, a second support shaft which is disposed so as to be in parallel to said first shaft and spaced from said first support shaft at a predetermined interval in the Z-axis direction, a third support shaft which is disposed so as to be in parallel to said first support shaft and spaced from said first support shaft at a predetermined interval in the X-axis direction, and first, second and third motors for adjusting said first, second and third support shafts respectively, and said adjusting plate member has a adjusting plate is supported on said first, second and third support shaft for supporting the projection unit which is equipped with a projection unit for projecting a picture to a screen and an angle-of-view adjusting mechanism for supporting the projection unit so that the position of the projection unit is adjustable and with which the picture projected from the projection unit is projected from the back of the screen, is characterized in that the angle-of-view adjusting mechanism has an adjusting plate for adjusting three degrees of freedom out of six degrees of freedom of the projection unit.